Influence Dietary Riboflavin Deficiency on Lenticular Glutathione Redox Cycle, Lipid Peroxidation, and Free Radical Scavengers in the Rat

Abstract

Effect of dietary riboflavin deficiency on rat lens glutathione, glutathione redox cycle, and oxidative-antioxidative processes was investigated to understand the possible biochemical mechanism(s) responsible for aggregation of lens proteins. Induction of riboflavin deficiency resulted in a marked reduction in the activity of glutathione reductase (GSH-R). Levels of glutathione (both reduced and oxidised) and sulfhydryl groups (total and non-protein), however, were unchanged. Activity of glucose 6-phosphate dehydrogenase, which generates the reducing equivalents, NADPH, necessary for maintenance of normal GSH-R activity, was found to be unaltered. On the other hand, glutathione dependent glutathione peroxidase, a potent peroxide scavenging enzyme, showed a significant rise in its activity with a concomitant increase in lipid peroxidation. Among the other antioxidative systems studied, superoxide dismutase and catalase remained unaltered, while levels of ascorbate declined.
These results indicate impairments in the glutathione redox cycle and antioxidative defence mechanisms, in addition to enhanced lipid peroxidation in the lens of riboflavin deficient rats.